The use of sorbent devices and/or dialysis devices for the removal of undesirable components, such as toxic constituents in blood are known in the art. It is also known that activated carbon is an excellent sorbent for removing organic metabolic wastes, drugs and other undesirable components from the blood. However, because of its high affinity for blood components as platelets, and its tendency to fragment, activated carbon has to be isolated from direct contact with blood in a hemoperfusion circuit. It is known in the art to encapsulate activated carbon particles in a polymeric coating, utilizing fine particles of activated carbon. However, studies have indicated that even with coated sorbents, the problem of microemboli still exists, and is related apparently to the technique of coating, the fragility of the coating, and to the construction of the devices using the coated sorbents. Moreover, it is known to coat activated charcoal particles by dispersing them into a solution of a polymeric binder, and then spinning the dispersion into fiber. The fibers serve to immobilize the carbon and prevent direct contact between the carbon and the blood. A dispersion of the powder activated carbon in a solution of alkali hydroxyethylcellulose (HEC) is extruded through a spinneret into an acid bath to coagulate the HEC into regenerated filaments. Such filaments are wound on a perforated spindle and sealed in a cartridge housing, with blood to be cleansed being pumped through the perforated spindle over the HEC solid filaments, and then out of the housing.
Even though various schemes of coating of sorbents as discussed above have been employed, studies have shown that the coated sorbents still may involve a microemboli problem of the carry-over of emboli of the sorbent into the vascular system. Moreover, in these prior art devices, nondesired sorption of certain blood or fluid components sometime occurs, which is detrimental to certain physiologic functions.